Detection of Raji binding activity in hyperimmune allogeneic tumor bearing sera associated with anti-BSA activity

Brown Norway (BN) rats were implanted twice with allogeneic (Lewis strain) Moloney sarcoma tumors (LM-2) and serum samples were assessed for Raji binding activity during primary and secondary tumor growth and rejection. Maximum Raji binding was observed 25 days after a primary tumor implant; thereafter, the binding activity decreased. Accelerated tumor rejection was observed after a second tumor implant and was associated with a 3-fold increase in serum Raji binding activity which remained elevated up to 40 days post-tumor implant. Raji binding activity in hyperimmune rats co-migrated with IgG in G-200 fractionated serum. Polyacrylamide gel electrophoresis (PAGE) revealed the presence of bovine serum albumin (BSA) on Raji cell membranes which reacted immunochemically with rabbit anti-BSA antiserum. Immunodiffusion studies revealed that sera from hyperimmune rats produced a precipitin band when reacted with Noniodet P-40 (NP-40) lysates of Raji cells and formed a line of identity with BSA.